Process for production of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane

ABSTRACT

A process for production of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane which comprises reacting phenol with 3,3,5-trimethylcyclohexanone in the presence of an acid catalyst wherein the reaction of phenol with 3,3,5-trimethylcyclohexanone is started in a slurry comprising phenol adduct crystals of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane and hydrated phenol in the presence of an acid catalyst, and then the reaction is continued in the slurry.

TECHNICAL FIELD

The invention relates to a process for production of1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (referred to as“BPTMC” hereinafter) in high yield and in high selectivity by an acidcondensation reaction of phenol with 3,3,5-trimethylcyclohexanone(referred to as “TMC” hereinafter) in a stable manner.

BACKGROUND ART

In recent years, BPTMC is used as raw materials for the production ofoptical products such as optical disks, as well as synthetic resins foroptical use such as polycarbonate resins for optical use. A variety ofprocesses for the production of BPTMC are already known. According toone of such processes, phenol is reacted with TMC using hydrogenchloride gas as a catalyst and an alkyl mercaptan as a promoter in thepresence of an inactive organic solvent or in the absence of a solventand then phenol remained unreacted is removed from the reaction mixtureby steam distillation, as described in Japanese Patent ApplicationLaid-open No. 2-88634. It is also described therein that, after thereaction, water is added to the reaction mixture, and then an alkali toneutralize the reaction mixture, followed by heating, cooling andremoving an aqueous phase, thereby obtaining the desired BPTMC asresidue.

A further process is known, as is described in Japanese PatentApplication Laid-open No. 8-505644. According to the process, phenol isreacted with TMC using hydrogen chloride gas as a catalyst and an alkylmercaptan such as octanethiol as a promoter. After the reaction, wateris added to the reaction mixture to form a slurry, and the slurry isfiltered to provide 1:1 adduct crystals of BPTMC and phenol, and thenthe phenol is removed from the adduct crystals, thereby providing thedesired BPTMC.

A process is also known, as described in Japanese Patent ApplicationLaid-open No. 4-282334. The process provides the desired BPTMC by thereaction of phenol with TMC using water-insoluble cation exchange resinshaving sulfonic acid groups therein as a catalyst and a mercaptancompound as a promoter. In Japanese Patent Application Laid-open No.5-213803, there is described a process in which an acid catalyst such asbenzenesulfonic acid is added to a mixture of phenol, TMC, a mercaptancompound as a promoter and water, whereupon the reaction is started withstirring, and the desired BPTMC is obtained in high selectivity.

As mentioned hereinbefore, BPTMC is used as raw materials forpolycarbonate resins for optical use. In order to supply BPTMC to thisuse, it is more and more strongly demanded to produce high purity BPTMCwhich is free of by-products derived from the reaction, and besides freeof high boiling point by-products or colored by-products derived frompurification processes for the obtained reaction product and residualphenol or trace impurities such as sodium.

It is essentially important to increase the selectivity and yield of thereaction to produce the desired high purity and high quality product ina stable manner. However, according to the known processes forproduction of BPTMC by the condensation reaction of phenol with TMC inthe presence of an acid catalyst, the selectivity of reaction is sosmall as about 70% so long as the present inventors know.

The invention has been accomplished to solve such problems as involvedin the known processes for the production of BPTMC by an acidcondensation reaction of phenol and TMC. Therefore, it is an object ofthe invention to provide a process suitable for industrial production ofBPTMC in high selectivity and in high yield in a stable manner.

SUMMARY OF THE INVENTION

The invention provides a process for production of1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane which comprisesreacting phenol with 3,3,5-trimethylcyclohexanone in the presence of anacid catalyst wherein the reaction of phenol with3,3,5-trimethylcyclohexanone is started in a slurry comprising phenoladduct crystals of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexaneand hydrated phenol in the presence of an acid catalyst, and then thereaction is continued in the slurry.

BEST MODE FOR CARRYING OUT THE INVENTION

According to the process of the invention for production of1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, the reaction ofphenol with TMC is started and carried out using an acid catalyst in thepresence of hydrated phenol which contains phenol adduct crystals ofBPTMC, so that the BPTMC generated in the reaction forms adduct crystalswith phenol immediately in the reaction mixture. Thus, the reaction iscarried out in a slurry from the start to the completion of thereaction.

In order to start and continue the reaction of phenol with TMC in thepresence of an acid catalyst in a slurry which contains phenol adductcrystals of BPTMC as mentioned above, it is preferred that, for example,phenol and water are placed in a reaction vessel before the reaction isstarted and, while the mixture of phenol and water (i.e., hydratedphenol), which is often referred to the starting liquid mixture, ismaintained at a temperature in the range of 15° C. to 40° C. at whichphenol adduct crystals of BPTMC do not decompose nor are soluble in thestarting liquid mixture, phenol adduct crystals of BPTMC are added tothe starting liquid mixture so that phenol adduct crystals of BPTMC arealready present in the starting liquid mixture before the start of thereaction. Subsequently an acid catalyst is introduced into the reactionvessel and then a mixture of TMC and phenol to start the reaction whilethe reaction mixture is maintained at the temperature in the range abovementioned throughout the reaction.

The amount of BPTMC present in the starting liquid mixture before thestart of the reaction depends on the temperature of the starting liquidmixture, but it is usually not less than 3% by weight, preferably in therange of 5-15% by weight of the phenol in the starting liquid mixture sothat BPTMC readily forms phenol adduct crystals therein.

When phenol is reacted with TMC in the presence of water using an acidcatalyst according to the known processes, the generated BPTMC isdissolved in phenol since the reaction mixture contains excess phenol.Accordingly, no adduct crystals are formed throughout the reactiondepending on the amount of phenol in the reaction mixture or thetemperature of the reaction mixture, or no adduct crystals are formeduntil the generated BPTMC exceeds its saturation solubility in phenol atthe reaction temperature, that is, usually for several hours after thereaction has been started.

In contrast, according to the invention, the reaction of phenol with TMCis started and continued using an acid catalyst in the presence ofhydrated phenol which contains phenol adduct crystals of BPTMC.Accordingly, BPTMC generated in the reaction forms adduct crystals withphenol immediately in the reaction mixture so that the reaction iscarried out in a slurry from the start of the reaction.

In this manner, the starting liquid mixture is a slurry which containsphenol adduct crystals of BPTMC, and the reaction is started in theslurry according to the invention. Consequently, BPTMC generated by thereaction of phenol with TMC forms phenol adduct crystals immediately inthe reaction mixture from the start of the reaction. Thus, BPTMCgenerated by the reaction of phenol with TMC is excluded as phenoladduct crystals or a solid phase from the liquid phase of the reactionmixture which contains phenol, TMC and water from the start of thereaction. Accordingly, undesired side reactions are suppressed, but alsothe desired reaction is promoted, and as a result, the selectivity andyield of the reaction improves.

The ratio of phenol (A) and TMC (B) both used as raw materials is in therange of 4 to 9, preferably in the range of 6 to 8, in terms of A/Bmolar ratio. In addition, aromatic hydrocarbons such as toluene, xyleneor mesitylene may be used together with phenol in an amount of 10% byweight or less based on the reaction mixture.

According to the invention, water is used together with phenol usuallyin an amount of 3-20% by weight, preferably in an amount of 5-15% byweight, based on the amount of phenol used in the reaction. The waterserves to form hydrated phenol and hence to lower the freezing point ofphenol, and besides, it serves to improve the absorption of hydrogenchloride gas of the reaction mixture when it is used as a catalyst,thereby to increase the reaction velocity.

The acid catalyst used in the invention is mineral acids such ashydrogen chloride gas, concentrated hydrochloric acid, concentratedsulfuric acid, phosphoric acid or methanesulfonic acid. These may beused singly or as a mixture of two or more. Among these mineral acids,hydrogen chloride gas is particularly preferred. On the other hand,phosphoric acid acts not only as an acid catalyst when it is usedtogether with another acid catalyst but also as a pH buffer agent forthe reaction mixture. Thus, phosphoric acid may be used together withhydrogen chloride gas.

It is possible to react phenol with TMC by using only a mineral acid asan acid catalyst, but it is preferred to use a thiol as a promotertogether with the mineral acid. The use of a promoter accelerates thereaction. Alkyl mercaptans of 1-12 carbons are preferred as the thiol,and as such thiols, there may be mentioned, for example, methylmercaptan, ethyl mercaptan, n-octyl mercaptan or n-lauryl mercaptan oralkali metal salts such as sodium salts of these alkyl mercaptans. Amongthese, sodium methyl mercaptide is in particular preferred. The thiol isused usually in an amount of 1-30 mol %, preferably 2-10 mol %, based onTMC used.

When hydrogen chloride gas is used as an acid catalyst, it is preferredthat the reaction is carried out in such a manner that the concentrationof hydrogen chloride gas in the gas phase in a reaction vessel is in therange of 75-90% by volume so that the yield of the desired reactionproduct improves, although the reason therefore has not yet beenclarified.

In order to maintain the concentration of hydrogen chloride gas in thegas phase in the reaction vessel at 75-90% by volume, the concentrationof hydrogen chloride gas is maintained at 75-90% by volume of the totalamount (100% by volume) of an inert gas such as nitrogen gas andhydrogen chloride gas in the vapor phase in the reaction vessel underthe atmospheric pressure, for example.

It is well known that generally in the reactions in which hydrogenchloride gas is used as a catalyst, the reaction is carried out whilethe concentration of hydrogen chloride gas in the reaction mixture ismaintained at a saturation concentration. In fact, the concentration ofhydrogen chloride in the reaction mixture can be easily maintained atthe saturation concentration by, for example, introducing 100% by volumedried hydrogen chloride gas into a reaction vessel continuously underthe atmospheric pressure. However, according to the invention, thereaction yield improves when the concentration of hydrogen chloride gasin the gas phase in the reaction vessel is adjusted in the range asmentioned above. The reaction yield decreases when hydrogen chloride gasis introduced into a reaction vessel in such high concentrations asabout 100% by volume, possibly because a part of BPTMC generated isdecomposed under such conditions.

In the process of the invention, the reaction temperature is usually inthe range of 15-40° C., preferably in the range of 20-30° C. When thereaction is carried out at the temperature as mentioned above, thephenol adduct crystals of BPTMC formed in the reaction are neitherdecomposed nor dissolved in the reaction mixture. Further, the reactionis carried out usually under the atmospheric pressure, however, thereaction may be carried out under increased pressures.

The manner in which phenol is reacted with TMC is not specificallylimited, however, as mentioned hereinbefore, it is preferred that phenolis reacted with TMC in the following manner. That is, either BPTMCcrystals, or at least a part of secondary filtrate residue which isobtained from the secondary crystallization and filtration and containsphenol and BPTMC and, if necessary, a part of primary filtrate which isobtained from the primary crystallization and filtration and containsphenol, BPTMC and by-products such as isomers or polymeric material, asdescribed hereinafter, is added to the starting liquid mixture composedof phenol and water to prepare a slurry containing phenol adductcrystals of BPTMC as described hereinbefore. Hydrogen chloride gas isthen introduced into the reaction vessel and the concentration ofhydrogen chloride gas in the gas phase is adjusted at 75-90% by volume.In this way, the hydrogen chloride gas is made into contact with theslurry while a mixture of TMC and phenol is added dropwise into theslurry in the reaction vessel to start and continue the reaction.

After the reaction, the resulting reaction mixture in the form of slurryis neutralized with an aqueous solution of an alkali such as sodiumhydroxide and is then heated to dissolve phenol adduct crystals of BPTMCin the reaction mixture so that the reaction mixture comes to asolution. Then water is removed from the solution, and the obtained oilysubstance is cooled to crystallize the desired phenol adduct crystals ofBPTMC out of the oily substance (primary crystallization). The phenoladduct crystals of BPTMC are then filtered and separated from the oilysubstance by suitable means, for example, by centrifugation while aprimary filtrate is obtained (primary filtration).

If necessary, the adduct crystals are further purified. For example, amixed crystallization solvent of aromatic hydrocarbon such as tolueneand water is added to the adduct crystals obtained in the primarycrystallization and filtration step to dissolve the adduct crystals inthe solvent preferably under increased pressure. The resulting solutionis then cooled to crystallize BPTMC and collected by filtration toprovide high purity BPTMC (secondary crystallization and filtration).

INDUSTRIAL APPLICABILITY

As described above, since the process of the invention for theproduction of BPTMC by the reaction of phenol with TMC in the presenceof an acid catalyst comprises starting the reaction in a slurry whichcontains phenol adduct crystals of BPTMC and continuing the reaction inthe slurry, the process provides BPTMC in high selectivity and in highyield in an industrially stable manner.

EXAMPLES

The invention is described in more detail with reference to examples,but the invention is not limited these examples.

EXAMPLE 1

112.8 g (1.2 mol) of phenol, 16.9 g of water, 0.5 g of 75% aqueoussolution of phosphoric acid and 7.2 g of BPTMCP crystals were placed ina one liter capacity four-necked flask provided with a thermometer, adropping funnel, a reflux condenser and a stirrer to prepare a slurry.The slurry was adjusted at a temperature of 20° C. After the inside theflask was replaced by nitrogen gas, hydrogen chloride gas was introducedinto the flask under stirring. The gas composition in the reactionvessel was analyzed and the volume concentration of hydrogen chloridegas was adjusted at 80%.

4.2 g of 15% aqueous solution of sodium methyl mercaptide was addeddropwise to the slurry while the slurry was maintained at a temperatureof 20° C., and then a mixture of 112.8 g (1.2 mol) of phenol and 42.0 g(0.3 mol) of TMC was added dropwise to the slurry over a period of sixhours. The reaction mixture was found to increase in temperature duringthe addition, and when the addition was completed, the temperature wasfound to be 40° C. Then, the reaction was further continued at atemperature of 40° C. for anther three hours under stirring untilcompletion. The reaction mixture was found to be slurry throughout thereaction from the start of the reaction when the mixture of phenol andTMC was added dropwise to the slurry to the completion of the reaction

The resulting reaction mixture was analyzed by liquid chromatography.The production yield (mol of BPTMC produced/mol of starting TMC used)was found 92.9%.

REFERENCE EXAMPLE 1

After the completion of the reaction described in Example 1, an aqueoussolution of sodium hydroxide was added to the reaction mixture in theform of slurry so that it was neutralized. The reaction mixture was thenheated to come to a solution and the solution was cooled to crystallizephenol adduct crystals of BPTMC out of the solution and the adductcrystals were collected by filtration (primary crystallization andfiltration).

Then, a mixed solvent of toluene and water was added to the adductcrystals, and the mixture was heated so that the adduct crystals weredissolved in the solvent. After removing water and cooling, theresulting purified crystals of BPTMC were collected by filtration(secondary crystallization and filtration).

The resulting secondary filtrate obtained by the secondary filtrationwas subjected to distillation to recover the toluene used as thecrystallization solvent while 38.5 g of distillation residue (secondaryfiltrate residue) containing 25.3 g (0.27 mol) of phenol and 12.8 g(0.04 mol) of BPTMC was obtained.

EXAMPLE 2

The volume concentration of hydrogen chloride gas in the gas phase inthe reaction vessel was adjusted at 90%, and otherwise in the samemanner as in Example 1, the reaction was carried out. As a result, theproduction yield of BPTMC was found to be 89.0%.

EXAMPLE 3

87.5 g (0.93 mol) of phenol, 16.9 g of water and 38.5 g of thedistillation residue (secondary filtrate residue) which had beenobtained in Reference Example 1 were placed in a one liter capacityfour-necked flask provided with a thermometer, a dropping funnel, areflux condenser and a stirrer to prepare a slurry containing phenoladduct crystals of BPTMC.

The slurry was adjusted at a temperature of 20° C. After the inside theflask was replaced by nitrogen gas, hydrogen chloride gas was introducedinto the flask under stirring. The gas composition in the reactionvessel was analyzed and the volume concentration of hydrogen chloridegas was adjusted at 70%.

4.2 g of 15% aqueous solution of sodium methyl mercaptide was addeddropwise to the slurry while the slurry was maintained at a temperatureof 20° C., and then a mixture of 112.8 g (1.2 mol) of phenol and 42.0 g(0.3 mol) of TMC was added dropwise to the slurry over a period of ninehours. The reaction mixture was found to increase in temperature duringthe addition, and when the addition was completed, the temperature wasfound to be 40° C. Then, the reaction was further continued for antherhalf an hour. The reaction mixture was found to be slurry throughout thereaction from the start of the reaction when the mixture of phenol andTMC was added dropwise to the slurry to the completion of the reaction

The resulting reaction mixture was analyzed by liquid chromatography.The production yield (mol of BPTMC produced/mol of starting TMC used)was found to be 92.2%.

COMPARATIVE EXAMPLE 1

112.8 g (1.2 mol) of phenol was used while the distillation residue(secondary filtrate residue) obtained in Reference Example 1 was notused, and otherwise in the same manner as in Example 3, the reaction wascarried out. The reaction mixture was found to be solution when thereaction was started (i.e., when the dropwise addition of a mixture ofphenol and TMC was started), but after three hours from the start of thereaction, the reaction mixture was found to be slurry on account ofphenol adducts of BPTMC generated in the reaction mixture.

The resulting reaction mixture was analyzed by liquid chromatography.The production yield of BPTMC was found to be 77.9%.

COMPARATIVE EXAMPLE 2

The volume concentration of hydrogen chloride gas in the gas phase inthe reaction vessel was adjusted at 97%, and otherwise in the samemanner as in Example 1, the reaction was carried out. As a result, theproduction yield of BPTMC was found to be 80.3%.

COMPARATIVE EXAMPLE 3

The volume concentration of hydrogen chloride gas in the gas phase inthe reaction vessel was adjusted at 60%, and otherwise in the samemanner as in Example 1, the reaction was carried out. As a result, theproduction yield of BPTMC was found to be 82.9%.

What is claimed is:
 1. A process for production of1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane which comprisesreacting phenol with 3,3,5-trimethylcyclohexanone in the presence of anacid catalyst wherein the reaction of phenol with3,3,5-trimethylcyclohexanone is started in a slurry comprising phenoladduct crystals of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexaneand hydrated phenol in the presence of an acid catalyst, and then thereaction is continued in the slurry.
 2. The process as claimed in claim1 wherein hydrogen chloride gas is used as an acid catalyst, and thereaction is carried out under hydrogen chloride gas of the concentrationof 75-90% by volume in the gas phase in a reaction vessel.
 3. Theprocess as claimed in claim 1 wherein the reaction is carried out at atemperature of 15-40° C.